Title page for etd-0823112-152224

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The technology trend of private branch exchange (PBX) for telephony communication has gradually shifted from the traditional time-division multiplexing (TDM) technology toward session initiation protocol (SIP) voice protocol by the network transmission on internet. The advantages of internet voice PBX is not only in the huge cost saving of international communication, but also the reduction of spending in hardware network and remote control investment. In this thesis, we use the Blackfin series chip BF533 platform provided by the Analog Device to build the Asterisk open source software for internet voice PBX and apply the SiliconLABs FXO/FXS chip solution to construct a complete set of IP-PBX system. The research of this thesis focuses on the simulation and analysis of the echo cancellation effect on the Asterisk IP-PBX in the public switched telephone network (PSTN).